Cacti Adaptations Photosynthesis Presented by Living Desert Zoo

Cacti Adaptations - Photosynthesis Presented by: Living Desert Zoo and Gardens State Park Carlsbad, New Mexico

Plants -Where Would We be Without Them? Every animal on earth depends on plants. Without plants, animals would not have food to eat or oxygen to breathe. Let’s find out how plants provide the food and oxygen that animals need to live.

Photosynthesis All plants make their food carbohydrates (a sugar called glucose) through photosynthesis. Plants need three things to make their food: 1. Light 2. Water 3. Carbon dioxide 1. The light comes from the sun, so photosynthesis happens during the day. 2. Water enters the plant through its roots and is carried by the stems to the leaves, where photosynthesis takes place. 3. Carbon dioxide is one of the gasses in the Earth’s air. It is the gas animals breathe out. Since plants don’t breathe way animals do, they have a different way to get the air in and out of them. Their leaves have pores called stomata that open and close.

Photosynthesis Photo means “light” and synthesis means “put together. ” So simply put, photosynthesis is the process of putting together carbon dioxide + water + sunlight and changing them into oxygen, water vapor, and food (a sugar called glucose).

Stomata - Windows of a Plant Stoma in a pea leaf Stoma in a tomato leaf The plants’ stomata are like windows. When they open, air comes in and goes out of the plant. While the leaves’ stomata are open, carbon dioxide comes into the plant and oxygen and water vapor pass out of the plant.

Glucose – Food for All The glucose stays in the plant and is used for growth and reproduction. When the plant is eaten by an animal, that food energy is passed on to the animal. When an animal eats another animal, it is getting some of the food energy that came from the plant.

Transpiration When oxygen is released through the stomata, water vapor is also released. The loss of water vapor through the stomata is called transpiration. Plants lose a lot of their water through transpiration. An acre of corn gives off about 3, 000 -4, 000 gallons of water each day. A fully grown tree can lose several hundred gallons of water through its leaves on a hot, dry day. About 90% of the water that enters a plant's roots is lost during transpiration. Water vapor is released during transpiration. Once water vapor reaches the leaf’s surface, it evaporates.

For most plants, the loss of water is not a problem. Their roots simply pull more water from the ground and their stems carry the water to their leaves. With cacti, the loss of water can be deadly for the plants. Since cacti live in dry places without much water, they can’t afford to lose their moisture into the air.